Manufacture of hollow cylindrical bodies

ABSTRACT

A method of producing a hollow cylindrical body of revolution in which there is welded to the outer peripheral surface of a metal sleeve a lower molten metal by means of a ring of molten metal surrounding the sleeve and the sleeve and ring of molten metal being relatively vertically displaceable. Other external layers can be applied successfully by the same method.

United States Patent R g t [451 Feb. 5, 1974 MANUFACTURE OF HOLLOW 2,299,747 10/1942 Harter 219/76 CYLINDRICAL BODIES 2,385,206 9/1945 Hopkins 164/52 1 2,427,350 9/1947 Carpenter et al... 219/76 Inventor: Gabriel g France 2,525,133 10/1950 Hopkins 164/52 [73] Assignee: Compagnie Des Ateliers Et Forges 223:: y :27 E '1" a 3 4 De La Loire Saint Chamond l 213,856 4/1879 Wheeler 164/98 x Flmlnya Etienne; Jacob 2,279,990 4/1942 Hopkins 164/252 Holtzer,C-A- ,France 2,385,206 9/1945 Hopkins 164/252 x 2,762,096 9/1956 Wittmoser 164/136 x [22] 1970 3,665,143 5/1972 Ujiie 219/73 x [211 App]. No.: 67,887

Primary Examiner-R. Spencer Annear [30] Foreign Application Priority Data Attorney, Agent, or Firm-Irving M. Werner Sept. 3, 1969 France 6930004 ABSTRACT 52] U.S. Cl 164/52, 164/98, 164/125, A method f pro ing a holl w cylindrical body of 164/252, 164/334 revolution in which there is welded to the outer pe- [51] Int. Cl B22d 27/02, B23d 19/00 ripheral rf f a m tal l e a low r molten [58] Field of Search... 164/50, 52, 94, 250, 252, 98, metal y means of a ring of molten metal Surrounding 164/125, 136, 334; 219/73, 76 the sleeve and the sleeve and ring of molten metal being relatively vertically displaceable. Other external [56] References Cited layers can be applied successfully by the same UNITED STATES PATENTS method- 1,533,300 4/1925 Baker 219/76 12 Claims, 12 Drawing Figures PAIENIEDFEB 51914 man 1 or 4 v GABRIEL eves-r ATTORNEY MANUFACTURE OF HOLLOW CYLINDRICAL BODIES B C RQUND. OF H NIIQHW.

This invention relates to the manufacture of hollow, cylindrical bodies, of alloy steel or the like, with or without an interior alloy lining. It also relates to the products thus obtained.

The present invention provides a cylindrical body of indefinite length, for example a thickwalled reactor sleeve, a thick-walled tube, etc., by depositing one or several layers of liquid metal around an initial cylindrical member which constitutes the internal lining of the said body.

The object of the invention is to produce a hollow, cylindrical body, the side wall of which is constituted by several layers one on top of the other, formed by one or different kinds of steel, the successive layers being closely welded together and being able to be hooped one to the other, the internal reactions of the materials or fluids contained or conveyed.

Numerous known methods lead to the obtainment of such products. In the present state of the art, there may be cited:

boilermaking methods by hooping sleeves one inside the other either hot or cold;

the methods of lining sleeves by means of a stainless steel lining inserted into a thick body either boilermade or forged;

the methods of internally filling bodies of boilermade or forged sheet metal with deposits of wire or strip solder;

the methods obtained by shaping and welding metal sheets or so-called plated sheets", obtained by various means and particularly hot sandwich rolling or plating by explosion;

the methods derived from the hooping of sleeves g! 35399 g p QSIBUPWS;

winding of coils in a spiral,

hooping of thin, super-posed shells, hooping by the action of withdrawing the longitudinal welds etc...,

methods of obtaining reservoirs by depositing solder in spirals etc....

In the field of the manufacture of very thick-walled tanks and reactors, the manufacturing difficulties are innumerable. Amongst these difficulties are the followthe difficulty of manufacture of boiler-made precision sleeves of very thick sheet metal, involving considerable machining;

machining of special joints on the inner surface of the body for the attachment of linings or sleeves;

difficulty, during the welding of longitudinal and circular joints, of obtaining slight local deformations;

difficulty of carrying out the internal filling with strip or wire in bodies of small diameter, including the necessity of very close tolerances during the production of the initial half-shells;

very high cost of articles made of plated steel and difficulty in working these sheets by hot forming without impairing the plating;

the long time necessary for carrying out the methods by winding or stacking thin metal sheets and difficulty in controlling circular welding of full thickness between these members;

difficulty in obtaining a correct thermal treatment from one layer to the other during the spiral welding. and poor efficiency of the welding material for this method since it is subjected to continuous use for too long periods.

SUMMARY OF THE lNVENTlON According to one aspect of the invention, a thickw alled tubeofci rculai section is obtained the grad ual deposition of liquid solder metal, under a layer of liquid slag according to the ESR method. This method being moreover characterized in that the deposition is effected in the form of a bath of annular section supplied at several points with metal, the bath being limited internally by a thin water-cooled sleeve, which will be the inner skin of the finished product, and limited externallyby a mold produced in the shape of a movable annular' shoe cooled by the circulation ofwater.

The apparatus for carrying out the method of the in vention comprises a plate with a vertical axis facilitating the centering of the thin sleeve; means for imparting to this plate a movement of rotation and oscillation; welding means comprising a series of machines using 583E166 of ver tical welding under siagfthese machines being distributed around the cylinder to be produced; means for imparting a relative movement of vertical translation between the plate supporting the body being produced and the platform supporting the welding means in such a way as to keep the level of the deposition bath and that of the welding means for supplying the bath in a relatively appropriate position; and an initial piece for starting the operation.

The product obtained by the invention is a hollow, cylindrical body of revolution, the wall of which, is of straight annular section of great thickness and which hast t fsi l aa sha estst iss a. it is formed by the superposition of V n coaxial sleeves, n being a whole number at least equal to 2, hereafter referred to in consecutive nu nber, the irtfitsiiatsifin the number 1 and the outer sleeve the number n;

b. the outer peripheral surface of the inner sleeve is that of a straight circular cylinder;

c. the sleeves 2, 3...n are tubes or sleeves of straight annular section of constant thickness over their entire length;

d. each sleeve is of a metal or a metallic alloy of' which can be either similar nature to or different from that of the other sleeve or sleeves V w W e. each sleeve envelops all he outer peripheral stirface of the preceding sleeve and is welded to the latter over the entirety of their contact surface;

f. the n sleeves, taking into account their respective widths and the admissible working load of the materials constituting each of them, confers on the wall of the body the necessary resistance for undergoing, without damage, the mechanical stresses to which it will be subjected when in service; 7 MUMWMWWM" g. the nature of the material and the thickness of the inner sleeve are chosen essentially in order to resist the physical-chemical action of the fluid which the cylindrical body has to convey or contain;

h. the nature of the material and the thickness of the outer sleeve is chosen essentially in order to resist the physical-chemical action of the ambient medium in which the cylindrical body has to remaimand i the nature of the rn a terial and the respective thicknesses of the sleeves 2, 3, n l, are chosen essentially in dependence on the mechanical resistance to be conferred on' the wall of the cylindrical body. Embodiments of the present invention will now b e described, by way of example, with reference to the accompanying drawings, in which:

i BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical section of apparatus for carrying out the present invention;

FIG. 2 is a plan view of the apparatus of FIG. 1;

FIG. 3 is a detail view of FIG. 1;

FIG. 4 is a sectional plan view of a modification of the invention;

FIGS. 5, 6, 8, to 12 show various examples of products produced by the present invention;

FIG. 7 is a sectional view of an example ofan internal sleeve used for carrying out the method according to the invention.

DESCRIPTION OF THE PREFERRED MBODI With reference to FIGS. 1 to 3 and as explained above, a thick-walled tube of circular section is obtained by the gradual deposition of liquid metal Eider, under a Iayer of liquid slag accordingtothe ESR (Electro-slag remelting) method. The deposition is effected in the form ofa bath of annular section supplied at several regions with metal, the bath being limited internally by a thin, brazed, water-cooled sleeve, which constitutes the inner skin of the finished product, and limited externally by a movable outer mold cooled by circulation of water.

In the embodiment shown in FIG. I, the apparatus comprises a plate 10, with a vertical axis, on which there is positioned and centered an inner sleeve 12 at commencement of production, and which supports the thick cylindrical body until the end of its manufacture. Means 14 are provided for imparting to this plate a movement of rotation or oscillation, the amplitude of which depends on the number of points of metal supply. In the case where the plate 10 does not rotate about its vertical axis, during deposition of the metal, the oscillating or rotating motion is imparted to the welding means described hereinafter.

The welding means, indicated generally at 16, is constituted by a series of machine using the ESR method of vertical welding under slag, these machines being located around the sleeve 12.

Each of these welding machines comprises a support 18 on which is placed a welding head 28 (double in the present case) and a system for supplying the metal to be applied. In the example shown, this supply system is it r a uble 99 fte FllP?" wound the metal 26 to be applied (strip, wire or band). A generator 34 is associated with each welding machine.

The plate 18 rests on a table 35, to which, as explained above, there may be imparted a rotating or oscillating movement by suitable means; not shown In FIG. 2 there is shown ah'emb'ddimenfivhich cornprises nine welding machines I to IX, similar to the machine described above. These nine machines are regularly distributed around the sleeve 12. In order to simplify the drawing only the axes of the machines II to IX have been shown.

In order to obtain a bath 37 of annular section, there is provided an external mold, in the form of a copper ring or shoe 30 which is water-cooled. This ring 30 is located around the inner sleeve 12 so as to proidel e i e n hese. w embers a QILQELLQLQ serving as a crucible for the metal to be applied. The

. welding machines are placed around this ring 30 in such a way that each undertakes the supply of one section of the liquid ring or bath 3:7.

In order to produce the outer covering for the sleeve 12 in the form of various concentric layers C to C (C, to C, for example) a movement of relative vertical translation is provided in order to keep the deposition bath at a suitable level in relation to the welding material ensuring the supply to this bath. This movement may be a descent of the product obtained or an ascent of the welding device, or a combination of the two simultaneously. In the latter case which is illustrated in the drawing, there is used, in conjunction a pit or depression into which the product produced can fall and a lifting plate 36 supporting the welding devices.

As in the ESR method of welding vertical longitudilar crucible and facilitating the start of the operation.

The liquid slag will be obtained from a solid granulated 40 flux by fusion inherent in this method of welding.

The inner sleeve 12 is cooled on its inner surface. The cooling may be obtained by a stationary ramp 33 causing water to run from its upper side or by a movable ramp 32 which sprays it at the height of the annulus of liquid metal. Only one of these methods need be employed.

As vvill be understood, the deposition of nie tal cons ti tuting successively each sleeve C C of the wall of the cylindrical body (FIG. 3), other than the internal sleeve 12, results from the solidification 38 of the base of a ring of liquid metal 37, initially formed at the base of the sleeve to be produced, around the preceding sleeve (C in the case of FIG. 3). This ring is produced by an application of liquid metal uniformly distributed over its surface. At the rate of the solidification of its base, due to this application, it rises progressively along the generatrices of the preceding sleeve. The volume of liquid metal of the ring is defined, in relation to the Speed f ss s s so as qbssin the ursfisfieaiea of the metal of the preceding sleeve with which it is in contact and, thus, effect the welding of the sleeve in the course of formation to the preceding sleeve, over all the entirety of their contact surface.

In the modification of the invention illustrated in FIG. 4, the thick-walled sleeve is made in sectors A, B, C, D, etc., obtained by vertical or helical deposition of several portions of symmetrical rings about the internal sleeve 12, by means of the U-shaped, water-cooled shoe 30'.

The sleeve 12 serving as an internal skin for the hollow, cylindrical body produced by the invention may have one of the following constructions:

It is constituted by a tube or a sleeve of annular section of relatively slight thickness (FIG. 5).

It is constituted by a tube or a sleeve of annular section of relatively slight thickness terminated at at least one of its ends by a full or annular end of revolutionfF,

F FIG. 6) the iifiiifai'sur'ta of Wiii'his substantially in the extension of the outer peripheral surface of the tube or of the sleeve 12.

It is constituted (FIG. 7) by several tubes or sleeves of the same annular section (12, 12"), placed end to end coaxially, one of the two end tubes or sleeves, or each of them, being terminated by a complete or annular end of revolution F, F, two consecutive tubes or sleeves being separated by an intermediate division wall of revolution Fi, the peripheral surface of all the end walls F, F or intermediate walls Fi being substantially in the extension of the outer peripheral surface of the tubes or sleeves 12, 12''.

There is shown in FIG. 5 a simple example of the ho]- low cylindrical body produced by the method of the invention. It can be seen that the wall of straight, annular section of substantial thickness of this body is formed by the super-position ofa plurality of coaxial sleeves C, to C FIG. 6 shows that the method of the invention makes it possible to obtain directly a reservoir or reactor in a single unit constituted by the lower and upper ends F and F and by its sleeve which is similar to that of FIG. 5.

In the example shown in FIG. 8, the body obtained comprises one or more outer flanges, such as flange 42, at-right angles to its axis of revolution and the internal bore of which is substantially in the extenf helicoidally (44) or parallel (46) to the generatrices Each of the bands are welded over their entire length on its two peripheral edges to the adjacent bands.

Finally, in the case of the helical arrangement, the sleeves may be formed from a single band, the width of which at the generatrices is equal to the pitch of the helix described by its edges which are welded together. The arrangement of bands parallel to the generatrices is another limit of the helical arrangement, corresponding to a zero inclination of their lateral edges in relation to the axis of revolution of the body.

Iii relation to the known methods herembefore briefly mentioned the method according to the invention obviates or mitigates:

all shaping operations on thick metal sheets and in-l termediate heat treatment between these shaping operations;

the difficult machining of shaped shells in order to obtain longitudinal and circular welding joints between each individual sleeve;

internal machining before filling;

internal filling operations by deposition of wires or strips, an operation generally effected in several layers;

the operation of circular welding between cylindrical bodies and forged bases or flanges, normally carried out in the actual manufacture.

Amongst other advantages obtained by the present invention there may be mentioned:

It facilitates the production of several concentric deposits successively, at different and quite separate times and with relatively short manufacturing periods, with metals which are identical or different from layer to layer and with forces less than those corresponding to the manufacture of a very thick liquid ring of the final total width to be obtained.

The risk of possible faults from one layer to the other can be reduced; since accidental faults possibly originating from a stoppage of current cannot statistically be produced on each layer at the same level. It is nevertheless possible to overcome these anomalies of structure by increasing the thickness to be obtained from the employment of an additional layer which would take into account all the aforesaid imperfections.

There may be effected by degrees the thermal treatment of the metal deposited during the deposit of one layer on the preceding layer. This thermal treatment may be made real and effective in this method since the parameters of the fusion operation are such that the progression of welding is relatively slow (between and 350mm vertical progress per hour).

It facilitates the successive deposition of several layers in order to obtain a hooping of each layer by the succeeding layer cooling on the former. There is created in the depth of the wall compression strain due to the construction, which acts in the opposite direction to that which is created in the sleeve during its use (operating pressure).

It makes it possible to reduce the total thickness of the wall obtained by standard calculations, due to these internal constructional stresses. New rules for calculation will be defined for this purpose.

It facilitates the direct production of a bimetallic body of the type of those required by the chemical industry, for example, a formic acid reactor, a urea reactor, etc. In fact it is possible to start with an internal sleeve of thin stainless steel which will then consequently be the internal skin of the thick-walled cylinder obtained. This inner layer can be continuously tempered during the operation of the manufacture of the thickness which is resistant to pressure.

By this means, it is possible to eliminate the operations of lining, inserting a sleeve, plating or internal filling at present practised.

Naturally, it is understood that the invention is not limited to the embodiments and the examples given above, but that it embraces all variations within the scope of the accompanying claims.

In particular, the method of electric welding under the protection of an electro-conducting slag, known as the ESR method, which has the advantage of providing a deposit of metal of high quality and which, in the preceding description is only mentioned for keeping the bath of metal molten the solidification of the base of which produces the deposit of metal progressively constituting the various sleeves of the cylindrical wall to be produced around the initial inner sleeve, is not exclusive for carrying out the invention. Many other methods of electrical welding for melting the metal to be applied. For example, either under a gaseous protection a more general manner, the bath may be supplied by any device capable of discharging liquid metal under an appropriate protection, while ensuring its t. a... it is to be appreciated that by the present invention it is possible to regulate the ascending speed of the ring of liquid metal as well as its temperature. If contemporaneous with this, the spacing of the cooling region on the inner surface of the body is regulated, in relation to the region of heating defined by the position of the ring of liquid metal and the intensity of cooling, it is possible to produce gradually on the sleeve preceeding that which is being deposited a normalization annealing. Furthermore, where the second sleeve is being deposited, either a tempering or a normalization annealing of the inner sleeve, is also achieved. Tempering or normalization annealing is determined by whether or not the second sleeve is stainless steel or other metal or metal alloy.

Normalization annealing is provided by controlling the penetration of a suitable heating means by displacing a heating element thereof at a constant speed from the bottom to the top of theside of the last sleeve. This is synchronized with the displacement of the cooling ramp disposed internally of the sleeve.

Having thus described the invention what is claimed l. A method of manufacturing a hollow, cylindrical body comprising the steps of:

a. providing an inner cylindrical sleeve,

b. laterally spacing from the inner sleeve a ring of copper having a base to define an annular zone therebetween having a base,

. delivering to the zone a supply of uniformly distributed liquid metal from several sources thereof which have relative motion around and along the longitudinal axis of the inner sleeve, said sources being equally spaced around the ring,

. depositing a ring ofliquid metal around the periphery of the inner sleeve in the zone, and

gradually solidfying a base of the ring of liquid metal to cause the formation of a surrounding sleeve of metal on the wall of the inner cylindrical sleeve.

2. A method of manufacturing a hollow, cylindrical body as defined in claim ll, including the step of gradually solidifying a base of the ring of liquid metal to form a next surrounding sleeve of metal on the preceding surrounding sleeve of metal.

3. A method according to claim 2, including the steps of laterally retaining the outer lateral surface of the ring of liquid metal; moving the ring of liquid metal along the axis of the sleeve such that the liquid metal is progressively deposited on the cylindrical body as the ring of liquid metal is progressively moved.

4. A method according to claim 3, including the step of forming at least one flange of metal around the periphery of the body.

5. A method according to claim 3, including, regulating the ascending speed of the ring of liquid metal, its temperature, the spacing of a cooling region in the inner surface of the body in relation to the region of heating defined by the position of the ring of liquid metal and the intensity of the cooling, so as to producegradually on the sleeve which precedes that which is being deposited a normalisation annealing or in the case where the second sleeve is being deposited, either a tempering or a normalisation annealing of the inner sleeve, according to whether the latter is of stainless steel or not.

6. A method according to claim 5 including, controlling the penetration of a heating means to normalize the annealing of the last sleeve deposited, displacing a heating element of the heating means at a constant speed from the bottom to the top outside of the last sleeve and synchronizing the displacement of a cooling m iamp disposed internally to the sleeve.

7. A method according to claim 1, including maintaining a high gradient of temperature between the peripheral sleeve being deposited and the inner or preceding sleeve, so as to obtain a hooping of each sleeve by that which follows it immediately in the order of deposition.

8. A method according to claim 1, including, forming a flange at right angles to the axis of revolution of the body atits lower end, the flange making it possible to begin the bath of liquid metal by constituting the base of the initial mold of the metal body.

9. A method according to claim 1, including forming the bath of liquid metal by the fusion of metalin the form of wires, sheets or strips, carried out under a layer of electro-conducting slag according to the method called re-melting under an electro-conducting slag and well known under the name ESR (Electro Slag Remelting).

10. Apparatus for manufacturing a hollow, cylindrical body, comprising a plate with a vertical axis facilitatin'g the centering of an inner sleeve; means for imparting to this plate a rotating or oscillatory movement; means forming a ring of liquid metal bath around the sleeve; ESR welding means comprising a series of ESR machines distributed around the cylindrical body to be produced said welding means feeding the bath; means for imparting a movement of relative vertical translation between the plate supporting the body being manufactured and the welding means to keep the level of the bath and of the welding means supplying the bath in relatively suitable positions; and a base for initially starting the forming operation of the body.

11. Apparatus according to claim 10, including, cooling means to uniformly cool the inner sleeve, the cooling means comprising a stationary ramp which causes water to flow from its upper edge.

12. Apparatus according to claim 10, including cooling means to uniformly cool the inner sleeve, the cooling means comprising a movable ramp which sprays water at the height of the ring of liquid metal. 

1. A method of manufacturing a hollow, cylindrical body comprising the steps of: a. providing an inner cylindrical sleeve, b. laterally spacing from the inner sleeve a ring of copper having a base to define an annular zone therebetween having a base, c. delivering to the zone a supply of uniformly distributed liquid metal from several sources thereof which have relative motion around and along the longitudinal axis of the inner sleeve, said sources being equally spaced around the ring, d. depositing a ring of liquid metal around the periphery of the inner sleeve in the zone, and e. gradually solidfying a base of the ring of liquid metal to cause the formation of a surrounding sleeve of metal on the wall of the inner cylindrical sleeve.
 2. A method of manufacturing a hollow, cylindrical body as defined in claim 1, including the step of gradually solidifying a base of the ring of liquid metal to form a next surrounding sleeve of metal on the preceding surrounding sleeve of metal.
 3. A method according to claim 2, including the steps of laterally retaining the outer lateral surface of the ring of liquid metal; moving the ring of liquid metal along the axis of the sleeve such that the liquid metal is progressively deposited on the cylindrical body as the ring of liquid metal is progressively moved.
 4. A method according to claim 3, including the step of forming at least one flange of metal around the periphery of the body.
 5. A method according to claim 3, including, regulating the ascending speed of the ring of liquid metal, its temperature, the spacing of a cooling region in the inner surface of the body in relation to the region of heating defined by the position of the ring of liquid metal and the intensity of the cooling, so as to produce gradually on the sleeve which precedes that which is being deposited a normalisation annealing or in the case where the second sleeve is being deposited, either a tempering or a normalisation annealing of the inner sleeve, according to whether the latter is of stainless steel or not.
 6. A method according to claim 5 including, controlling the penetration of a heating means to normalize the annealing of the last sleeve deposited, displacing a heating element of the heating means at a constant speed from the bottom to the top outside of the last sleeve and synchronizing the displacement of a cooling ramp disposed internally to the sleeve.
 7. A method according to claim 1, including maintaining a high gradient of temperature between the peripheral sleeve being deposited and the inner or preceding sleeve, so as to obtain a hooping of each sleeve by that which follows it immediately in the order of deposition.
 8. A method according to claim 1, including, forming a flange at right angles to the axis of revolution of the body at its lower end, the flange making it possible to begin the bath of liquid metal by constituting the base of the initial mold of the metal body.
 9. A method according to claim 1, including forming the bath of liquid metal by the fusion of metal in the form of wires, sheets or strips, carried out under a layer of electro-conducting slag according to the method called ''''re-melting under an electro-conducting slag'''' and well known under the name ESR (Electro Slag Re-melting).
 10. Apparatus for manufacturing a hollow, cylindrical body, comprising a plate with a vertical axis facilitating the centering of an inner sleeve; means for imparting to this plate a rotating or oscillatory movement; means forming a ring of liquid metal bath around the sleeve; ESR welding means comprising a series of ESR machines distributed around the cylindrical body to be produced said welding means feeding the bath; means for imparting a movement of relative vertical translation between the plate supporting the body being manufactured and the welding means to keep the level of the bath and of the welding means supplying the bath in relatively suitable positions; and a base for initially starting the forming operation of the body.
 11. Apparatus according to claim 10, including, cooling means to uniformly cool the inner sleeve, the cooling means comprising a stationary ramp which causes water to flow from its upper edge.
 12. Apparatus according to claim 10, including cooling means to uniformly cool the inner sleeve, the cooling means comprising a movable ramp which sprays water at the height of the ring of liquid metal. 